Topic: Won't Idle on all four - Kawi KZ550 - Almost got it figured out!!!

[KB02]

Okay, so I have gotten my '80 KZ550c to the point that it runs and rides under it's own power once again. But now I have come across a very strange problem.

I just finished syncing the carbs (With a Mercury style meter) and, while everything else looks good, I have the strangest inconsistant idle. If you start the bike and let it run, it will run just fine. No problems. Even with the occational rev, it goes back to a normal idle. BUT, as soon as the bike is physically moved; picking it up off the side stand, sitting on the bike, bouncing on the bike (I kid you not), the idle jumps about 1-2000 RPMs. I don't know the exact RPMs that it hits or the amount that it jumps as the tach cable is broken. I never noticed it doing this before, but I also havn't been riding it much do it needing work (The bike has yet to see the outside of my neighborhood without being on a trailer). What could possibly be causing this to happen?

The bike is running lean, if that's a clue to anyone. I am running pods rather than an airbox due to the airbox being MIA when I bought the bike (Exauhst is stock). Would this lean condition be part of the problem? Why would the idle be effected by physical movement of the bike?

That brings up another question. When I was balancing the carbs, #3 was my biggest problem. While #'s 1, 2 and 4 were pulling at about 24-26 on the meter, #3 was haning out at around 16-18. I could not adjust #3 any higher than that. It was at the end of the adjustment range. What I ended up doing was dropping the other three down to meet #3. The result was a much smoother idle, untill the bike was moved. That's when I became really confused

I had bench synced the carbs before putting them on the bike.

Any Ideas?

[crazypj]

did you do valve clearance and timing first? (I know its shim under bucket but it still has to be right, done a bunch with bad exhaust valve seal/burnt valves) you need to fix lean mix probs, they were real lean even with the stock airbox, it aint going to adjust out with mix screws. You also need to do it with bike upright, the fuel levels are probably changing just enough to make a difference.
for anyone who is interested,
Shim type motors, the valve clearances get tighter as the valve seat wears faster than thre shim/cam/bucket due to the extra bearing surface in this ype engine.
Screw and locknut, the screw and valve tip wear faster than valve face/seat so clearance gets bigger
( line contact with shim versus point contact with screw)
PJ

[KB02]

Vavle clearance are fine. The exhaust is a little tight, still, but it's much better than what it was. What I got the bike, the #3 exhaust valave had no clearance at all. It was crazy.

Timing is spot on, too.

[cb650]

Floats?




                 Terry

[KB02]

Well, that one of the only things that I can thnk it might be. Maybe a float thats too high spilling into the engine whe its rocked. Would that make sence?

I haven't had time to check that yet.

[dusterdude]

im thinking float height too.

[Ibsen]

If the valves are ok, the only things I can think of that can cause that difference in the vacum reading is either a low compression in that cylinder, or an air leak in the intake for that carb. And the unstable idle could be a result of this. Also, if you have got too little freeplay in the trottle cables it might cause the idle speed act like that. The dual cables on the KZ's has to by synched differently than the dual cables on a Honda btw.

[cb650]

I just cleaned the carbs on a 84 kz 550 and it only had the pull.   No spot even for a return.




                           Terry

[KB02]

My '80 has the push/pull cables. The slack on the cables is set as specified (or as close as I can get to it) in the clymers manual.

I've got tomorrow off. The first thing I'll do is check the float hieghts and see what's what. After that it's time to pull the engine. I'm having it media blasted to get it cleaned up. I'll let you know what I find.

[crazypj]

Vavle clearance are fine. The exhaust is a little tight, still, but it's much better than what it was. What I got the bike, the #3 exhaust valave had no clearance at all. It was crazy.

Timing is spot on, too.

you want to set it at least 0.001" slacker than spec. if it was tight the valve seat will be a bit burned. setting it loose allows it to 'hammer back' into shape
the shims are 13mm, dont know how much they cost now, used to be 0.89 pence british (about$1.90), probably gone up a bit since i last did one. I have a full set but they are at my brothers in Britain (I'm in Florida)

[KB02]

Okay, so float hieghts are all fine and consistant across the board. I did notice that I had one coil connection that was very loose. I practically fell off while I was taking the coils off. (engine is now sitting on a stand on my Garage floor). I lso noticed that when I took off the throttle close cable, I heard what sounded like the throttle slamming shut. I'm pretty sure there was slack on the line, but I guess there was a possibility that it wasn't.

SO, here's my new theory:
   The engine, while sounding a little rough at idle (really sounded fine, just a touch rough. I never thought anything of it) it was only running on two cylinders. While shaking the bike, the connection was made for that coil and, with the throttle at a bit of a pull from the close cable, it reved up to what it was supposed to be. When connections was lost again, the bike dropped back down to the lower idle on just two jugs.

What do you all think? The engnine is currently out and getting ready to go off for a good clean up with glass beads while I give the frame a good scrub down. Let me know what you think and I'll let you know what I find when I throw everyting back together.

[KB02]

Okay, forget my "New Theory" in that last post. It's garbage.

Sorry to bring up an old post, but I still need help on this one.

So the engine is back from the cleaners. It is back in the bike everything is connected, Electrical connectors on coils have all been replaced. Idle is still screwed up.

So here is the refined issued: The bike will not idle on all four cylinders. I am thinking, now, that it is only idling on three. Occationally you will here a pop of the forth kicking in. (you know what they say, three out of four ain't bad, which is why it doesn't sound awfull when idling, just a bit rough). Rev the bike and all four kick in without an issue. As the bike sits idling, if you physically move the bike, take it off the side stand, jump up and down on the seat, etc..., the forth cylnder will kick in and the bikes runs like it should for a second, then jumps back down to the rough idle.

I am not 100% positive, but I think it is Cylnder #4 that keeps cutting out on me.

The next time that I will have time to work on the bike will be thursday evening. Here is what  am planning to do:
I am going to re-check compression on all four jugs.
I am going to re-synch the carbs.
Since it will occationally pop on the forth, I don't think I have any clogged jets, but should I ckeck the idle jets anyway?
What else should I be looking for?

[tazzmann]

Sound to me like a loose wire somewhere. If the engine is actually cutting in and out when moved, then it is not a fuel issue. I would start at the advancer and work my way backwards to the coil. This is how I found a loose connection on my KZ650.

[KB02]

The plug wires are a bit old and stiff. And someone else on a Kawi board also mentioned the thought of a bad wire. I'm going to replace the plug wires and see if that helps. Luckily, it is designed to have replacable coil wires. AND I'll probably check the idle jets just one more time... you know... just to make sure that I don't get out of practice on them.

[KB02]

Okay, forget the electrical. Everything is fine. Grrr... which means that I am back to my carbs... Double Grrrr...

I know its getting gas. I know there is ample compresion and suction coming from the cylinder. And the Jets are clear. What now? There are no air needles to adjust on these carbs, but that's the only other thing that I can check is air flow.

[tazzmann]

How did you determine that it is not electrical? Unless you pulled every single connection apart, you may have a connector that is together, but corroded on the inside causing connection problems. Just a thought...

[KB02]

Well, that's pretty much how I determined that it wasn't eletrical, I pulled every connector (that was releated to ignition or was even close to a plug that was related to ignotion) apart and checked them out. Only a few were dirty. Remarkable, none of them were corroded.

Plus, while I had the air filter off of the problem child (Cylinder #4), I was able to squirt some gas straight through the carb and engine picked up. If the plug was not firing, it wouldn't have done that... right?

[tazzmann]

That is correct which suggests a fuel delivery problem in that cylinder. I would check the fuel level in that carb. That is one of the easier things to check first.

[KB02]

float hieght is as specified in service manual. I tried both lowering and raising it with no effect either way.

It's almost the air fule ratio is off, but there is no mixture screw to adjust. Weird, huh?

[tazzmann]

Do you have stock carbs? The air mixture screw might be under a cap that is pressed in. you can get the cap off by drilling a small hole in it then getting a stiff piece of wire to act as a hook and pop it out that way. A screwdriver works as well. Also on some carbs the mixture screw is UNDER the carbs toward the front. Can you post some pics of your carbs?

Also another thing to check is air leaks around the carb boots. With the engine running, spray some WD40 on the carb boots where it meets the head and where is meets the carbs, if the idle changes or the cylinder seems to "kick in", then it might just be an air leak, though from your symptoms I highly doubt it. But hey, just one more thing to eliminate.

[KB02]

Yeah, I think it's the pressed cap design that I have after further inspection (and suggestions from a Kawasaki forum). I've got tomorrow off, so I'm going to take a drill and see what I can do without destroying the carbs.

This bike is really starting to get on my nerves, if you know what I mean.

[tazzmann]

I know exactly what you mean. 

The caps are pretty thin, so it shouldn't take too much to drill through them. Then just take a small screwdriver and pop them out. I would turn the screws in to lightly seated counting the number of turns. Write that number down and then pull the screws all the way out. Replace the o-ring on the ends and then screw them all the way back in to lightly seated and then back them back out the same number of turns you counted earlier. This should get you back in the ballpark.

Hope this helps!

[KB02]

Grrrrr......

Air screw screwed all the way in, air screw sitting in my hand... no difference either way. And no difference at any point in between.

Damn it!!!

What the hell is wrong with this bike?

[tazzmann]

replace the o-ring on the air screw? They tend to flatten out over time and create a small air leak. When that happens you can screw it in or out all day long and it won't change a thing.

[dusterdude]

if there is no diff with the air screw in or in your hand,sounds like there may be trash in the air screw circuit.